Background. Staphylococcus aureus endocarditis has a high mortality rate. Vancomycin minimum inhibitoryconcentration (MIC) has been shown to affect the outcome of methicillin-resistant S. aureus bacteremia, and recentdata point to a similareffect on methicillin-susceptible S. aureus bacteremia. We aimed to evaluate the effect of van-comycin MIC on left-sided S. aureus infective endocarditis (IE) treated with cloxacillin.Methods. We analyzed a prospectively collected cohort of patients with IE in a single tertiary-care hospital.Vancomycin, daptomycin,and cloxacillinMICwas determinedby E-test. S. aureus strainswere categorizedas low van-comycinMIC(